# How do you solve x^2-8x=9?

Jun 16, 2018

See a solution process below:

#### Explanation:

First, put the equation in standard form:

${x}^{2} - 8 x = 9$

${x}^{2} - 8 x - \textcolor{red}{9} = 9 - \textcolor{red}{9}$

${x}^{2} - 8 x - 9 = 0$

Next, factor the left side of the equation as:

$\left(x + 1\right) \left(x - 9\right) = 0$

Now, solve each term on the left side of the equation for $0$:

Solution 1:

$x + 1 = 0$

$x + 1 - \textcolor{red}{1} = 0 - \textcolor{red}{1}$

$x + 0 = - 1$

$x = - 1$

Solution 2:

$x - 9 = 0$

$x - 9 + \textcolor{red}{9} = 0 + \textcolor{red}{9}$

$x - 0 = 9$

$x = 9$

The Solution Set Is:

$x = \left\{- 1 , 9\right\}$